Locationing systems can track mobile targets in real time. These systems typically ascertain information relating to their geographic locations based on communications with a variety of different wireless locationing systems (e.g., the Global Positioning System (GPS), cellular network systems (e.g., GSM), and wireless local area networks (e.g., a system of Wi-Fi access points). No single approach, however, provides continuous tracking information under all circumstances. For example, GPS tracking requires a tracking device to have an unobstructed view of at least four GPS satellites at the same time, making GPS tracking in urban and indoor environments problematic. Dead-reckoning may be used to supplement GPS locationing when GPS signals are unavailable or inaccurate (e.g., as a result of signal multipath error). However, dead-reckoning navigation is limited by the rapid accumulation of errors and, requires a complex fusion process to integrate dead-reckoning navigation data with GPS navigation data. Map-matching techniques can improve locationing accuracy by identifying the most likely locations of a vehicle on a road network. However, the accuracy of map-matching techniques depends significantly on the accuracy of the position estimates for the mobile target being tracked and the fidelity of the spatial road map used to locate the mobile target in a geographic region.